Fuel injection unit



Nov. 10, 1959 R. H. L'ORANGE 2,912,168

FUEL INJECTION UNIT Filed March 1, 1957 2 Sheets-Sheet 1 91 INVENTOR.

RUDOLF HEINRICH L'ORANGE ATTORNEY Nov. 10, 1959' Filed March 1, 1957 2Sheets-Sheet 2 INVENTOR.

RUDOLF HEINRICH LORA/VGE ATTORNEY.

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FUEL INJECTION UNIT Rudolf Heinrich LOrange (deceased),

Freudenstadt, Germany, b.H., Glatten, many Unite Glatten, Kreis assignorto LOrange Gm. Wurttemberg, Germany, a firm of Ger- The presentinvention relates to a fuel injection device for internal combustionengines in which the fuel pump is combined with the fuel nozzle to forma unit.

One of the numerous difliculties preventing general use of a combinedfuel pump and nozzle unit is the fact that the unit must be placed closeto the combustion chamber so that the pump is exposed to hightemperatures causing heating of the pump in addition to heating by theheat produced by the work of the pump.

Other difficulties are caused by the necessity of making at least theportion of the pump nozzle unit which is proximal to the combustionchamber very small so that there is sufficient space left for otherelements which must be provided at the same locality, for example, inletand outlet valves. Because of this requirement, the fuel pumps ofconventional injection devices are spaced from the combustion chamberand from the fuel nozzle. This involves undesired dead spaces andadditional joints which must be sealed.

It is an object of the present invention to provide a fuel injectionpump and nozzle unit which overcomes the diniculties experienced withconventional fuel injection devices by directly and tightly seating anozzle cap member, which have at least one atomizing orifice, on theguide sleeve for the fuel pump piston.

In the unit according to the invention only one packing or seal isneeded against the very high pump pressure which is of advantage and isavailable in pump and nozzle units. This seal must be tightened onlyonce when the device is assembled. All other elements required at thehigh pressure portion of the device are accommodated within the nozzlecap member which forms part of the high pressure pump chamber. Theseelements include one or more pressure valves, a nozzle valve which maybe in the :form of a simple check valve or of a back pressure valve,:and auxiliary elements serving to supply, distribute, or whirl the fuelprior to its exit through the atomizing aperture or apertures.

The pump nozzle unit according to the invention is additionally improvedby cooling the pump chamber by means of excess fuel. Since the nozzlecap member is in direct contact with the guide for the pump piston, thecap member forms a part of the pump chamber and benefits from thecooling action of the flowing fuel, there being no intermediate partswhich interfere with heat conduction and heat transfer. The same is thecase with the elements which are located inside of the nozzle cap,particularly the pressure valve and its seat.

The novel features which are considered characteristic of the inventionare set forth with particularity in the appended claims. The inventionitself however and additional objects and advantages thereof will bestbe understood from the following description of embodiments thereof when'read in connection with the accompanying drawing, in which:

Fig. 1 is a longitudinal sectional view of a pump nozzle unit accordingto the invention taken in a flat plane including the vertical axis ofthe pump nozzle unit;

Fig. 2 is a longitudinal sectional view of a modified pump nozzle unitaccording to the invention taken in a flat plane including the verticalaxis of the pump nozzle unit.

Referring moreparticularly to Fig. 1 of the drawing, numeral 1designates a casing having a cavity 1 containing a guide sleeve 2 for apump piston 3 having an upper extension 3'. The lower part of the sleeve2 is provided with a flange 4 abutting against an internal annularshoulder 5 of the casing 1. The axial extension 4' of the flange 4 issmaller than the thickness of the wall of the sleeve 2 and is so smallthat the sealing pressure applied to the flange cannot deform thecylindrical portion 2' of the sleeve. The lower surface 4" of the flange4 is plain and is abutted by the upper end 6' of a nozzle cap member 6.The latter has a substantially cylindrical portion 6", a pressure valve7 and a seat member 8 for the pressure valve. Also contained in the capmember 6 is an intermediate plate 9 which limits the down stroke of thevalve 7, a nozzle valve 10, and an intermediate member ll having bores11 through which the fuel flows into a chamber 12 from which the fuel isdischarged through an atomizing orifice 13 in the bottom of the capmember 6.

The nozzle valve 10 has a cylindrical portion 91 and a frustoconicalportion cooperating with valve seats 14 and 15, respectively, providedat the lower end 16' of a seat element 16, the seat 14 beingcylindrical, corresponding to the cylindrical valve portion 91. Thevalve 10 is pulled onto the seats 14 and 15 by means of a coil spring 17interposed between the element 16 and a shoulder 10' provided on theupper end of the stem 18 of the valve 10. The space 13 between the lowerseat 14 and the orifice 13 is small.

The pump piston 3 is actuated by a tipping lever 19, of which only aportion is shown, through a pusher 2t). Adjustment is effected byrotation of the piston 3. For this purpose a rotatable regulating shaft21 is provided with a worm 2i cooperating with a worm. wheel 22' formingpart of a regulating element 22 mounted on a sleeve 23 which isrotatable on a cylindrical upper extension 1" of the casing l.Interposed between the element 22 and the sleeve 23 is a Vernier ring 24coacting with a pin 25 mounted on the element 22 and a pin 26 mounted onthe sleeve 23. The lower end 23' of the sleeve 23 is provided withrecesses 23" receiving pins 27 extending radially from a member 28 whichis mounted on the extension 3' of the piston 3.

The fuel is supplied through a channel 29 in the casing 1 which channelcommunicates with an internal annular recess 39. The latter communicateswith an inlet port 31 of an axial channel 32 in the interior of thepiston 3. The lower end 32 of the channel 32 communicates with the pumpchamber 33. The latter is formed by the interior of the piston guidesleeve 2, the seat member 8 of the pressure valve 7, and the uppercylindrical portion of the cap member 6. These parts are, therefore,cooled by the cold fuel. At the beginning of the working stroke of thepiston 3, the inlet port 31 is closed because the latter moves below theannular recess 30 so that the fuel opens the valve 7 and flows throughthe valve 10 into the atomizing orifice 13 until a helical groove 34 inthe piston 3 communicates with a pocket 35 having a helical edge in thelower end of the pump sleeve 2. From this moment the fuel flows throughthe groove 34 back into a fuel return conduit 36 in the casing 1.

Fig. 2 shows a modified arrangement in which the fuel supply to theworking space of the pump is terminated by a suction valve 40, the otherparts of the pump nozzle unit being substantially equivalents of thecorresponding parts of the device shown in Fig. 1.

The device shown in Fig. 2 operates as follows:

The liquid fuel enters through an inlet element 41 and passes through afilter 43 into a supply channel 44 in a casing 45. Channel 44communicates with an internal annular recess 46 of a pump piston guidesleeve 47. The recess 46 communicates through ports 43 in a pump piston49 with an axial bore 50 in the piston 49. The suction or fuel admissionvalve 40 closes the lower end 50' of the bore 50 and moves relatively tothe piston 49 because of its inertia. Since the pump piston is in theouter dead center position during the greater part of a revolution of acam 51 actuating a lever 52 which operates the piston 49, the fuel flowsinto the pump chamber 53 during the greater part of a revolution of thecam 51. The valve 40 is held in the bore 50 by a weak spring 54 and thefuel flows freely past the valve 4%) when the piston is in the outerdead center position. The relatively cold fuel cools the sleeve 47, aseat member 55 for a pressure valve 56, and a nozzle cap member 57. Aslong as the pump piston is in the outer dead center position, the fuelflows through an opening 61 in the sleeve 47 into a return bore 58 inthe casing 45 and through a bore 59 to an outlet element 60.

When the piston 49 is moved towards the inner dead center position andhas passed the fuel return opening 61 fuel injection begins and lastsuntil a helical groove 62 on the outside of the piston 49 has reached acontrol opening 63 in the sleeve 47 so that the pump chamber 53 isrelieved through a channel 64. When the pump piston 49 begins itsoutward stroke the suction valve 40 opens because of its inertia andbecause of the pressure of the fuel entering through the conduits 46 and48. Fuel flows again through the pump chamber 53, cooling the adjacentparts.

The fuel passing the pressure valve 56 flows to the nozzle valve 33. Thelatter is held in closed position by means of a spring 65 until the fuelpressure overcomes the resistance of the spring. The pressure needed foropening the valve 83 is defined by the spring 65 and by the diameter ofthe valve seat 66. During the first part of the opening movement of thevalve 83 the valve remains substantially closed because of the provisionof a cylindrical or piston portion 67 on the valve 83, the portion 67fitting into a corresponding cavity 68 in the seat member 68. Thediameter of the portion 67 makes the opening of the valve 83 labile sothat at low speed and little fuel supply the valve will close after aninitial opening until suflicient fuel pressure is accumulated forreopening the valve. When the valve closes after termination of theinjection the portion 67, because of its relatively great diameter, actsas a suction piston relieving the space 69 in the nozzle end of the capmember 57 and sucking fuel back from the nozzle orifice 70 for avoidingdripping of fuel which is still under considerable pressure into thecombustion chamber.

The bottom end 47' of the sleeve 47 is provided with a flange 70 ofrelatively small axial extension which abuts against an annular shoulder45' in the cavity 45" of the casing 45 which cavity receives the sleeve.The upper end 57' of the cap member 57 is pressed against the flange 70by means of a nut member 71 which is screwed into the lower end 84 ofthe casing 45. Pins 72 fitted into suitable radial bores in the casing45 extend into suitable recesses 85 in the flange 70 as well as in theupper end of the cap 57 to prevent relative rotation which is ofparticular importance when assembling and dismantling the device.

The fuel pressure produced during the working stroke of the piston 49amounts to between 14,220 p.s.i. and 28,440 p.s.i., depending on theconfiguration of the cam 51, on the tension of the spring 65, and on thesize of the atomizing orifice 70.

It is a particular advantage of the pump nozzle unit according to theinventionthat the aforesaid injection pressures, if required by thecombustion arrangement of the engine in connection with which the unitis used, can be employed in plants which are exposed to considerablevibrations and the like.

It is important that escape of fuel between the sleeve 47 and the piston49 be prevented. In the embodiment shown in Fig. 2 fuel flowing from thespace 53 along the piston is received in an annular space 64-. Thepressure in the latter is lower than the Working fuel pressure; thereturn flow, however, develops sporadic back-pressures which come closeto the working pressure of the fuel. Fuel flowing farther upwards alongthe piston 49 reaches the annular space 46 into which fuel is suppliedand whose pressure is usually not more than 30 p.s.i. Even at this lowpressure fuel passes along the piston. This fuel is caught in an annulargroove or recess 73 in the sleeve 47 from which it is removed through aconduit 74 which is separated from the fuel supply conduit 44 as well asfrom the fuel return conduit 59. This separation is important asotherwise the pressure in the conduits 44 or 58 reaches the leakagechamber 73 and forces fuel out of the pump nozzle unit.

For obtaining a tight seal against leakage of fuel collected in therecess 73 the sleeve 47 is provided with two annular steps 86 and 87,one below and one above the recess 73. The steps are opposed tocorresponding annular shoulders 88 and 89 in the cavity of the casing45. Packings 75 and 76 are pressed between the opposed steps andshoulders. The packings must resist the fuel and must be elastic. Theyare preferably made of pure aluminum, i.e., of a material containingabout 99% aluminum.

It has been found of advantage to provide the upper packing 75 with agreater initial tension than the lower packing 74.

Since the pump nozzle unit requires a fuel supply conduit and a fuelreturn conduit, and, in addition, a third conduit for low pressureleakage fuel, a special column member 77 has been provided accommodatingthree conduits and extending outside of the cover 78 for the enginecylinder head, a fuel supply nipple 79 and return and leakage nipplesbeing screwed into the top of the column 77.

The pump nozzle unit is held on the engine cylinder head 30 by means ofa bracket 81 which presses against the casing 45. The latter pressesthrough the cap member 57 and the nut member 71 against a soft packing82 resting on the cylinder head and sealing the combustion space againstthe pump nozzle unit.

What is claimed is:

1. A fuel injection unit for internal combustion engines, comprising acasing, a pump including a sleeve member disposed in said casing, a pumppiston reciprocable in said sleeve member, a nozzle means including amember having a hollow substantially cylindrical portion extending intosaid casing and placed coaxial of and endwisely abutting said sleevemember, an annular groove in said sleeve member opposite the portion ofsaid piston which is distal of said nozzle means for receiving fuelleaking along said piston, the outside of said sleeve member beingprovided with two axially spaced annular steps, one of said steps beingon a radial plane below said groove, the other of said steps being on aradial plane above said groove, said casing being provided with twoaxially spaced annular steps placed opposite the steps on said sleevemember, leakage removal conduit means in said casing and extendingbetween said steps, and packing rings individually placed between theopposed steps of said sleeve member and of said casing. 1

2. A fuel injection device according to claim 1 in which said packingrings are made of substantially 99% pure aluminum.

3. A fuel injection device according to claim 1 including a columnmember laterally connected with said casing, said column member beingprovided with a leakage fuel removal channel connected with said leakageconduit means, a fuel supply channel for conducting fuel to said pump,and an excess fuel return channel for returning excess fuel from saidpump.

4. A fuel injection device according to claim 3 including a filterelement placed in at least one of said channels.

5. A fuel injection unit for internal combustion engines, comprising acasing, a sleeve in said casing, a hollow pump piston reciprocal in saidsleeve, a fuel supply conduit extending through said casing and throughsaid sleeve, a port in said piston for admitting fuel from said conduitinto the interior of said piston, a nozzle cap member secured in saidcasing and abutting against said sleeve and forming a pump chamber withsaid sleeve, the interior of said piston communicating with saidchamber, a fuel return conduit communicating with said pump chamber andextending through said sleeve and said casing and being controlled bysaid piston for returning excess fuel from said chamber upon apredetermined position of said piston for cooling said cap member, and avalve disposed in the hollow of said piston for closing the hollow ofsaid piston against said pump chamber.

6. A fuel injection unit for internal combustion engines, comprising apump including a sleeve member, and

a pump piston reciprocable in said sleeve member, a nozzle cap memberhaving a hollow cylindrical portion coaxial of said sleeve member andendwisely abutting against said sleeve member, said cap member having abottom provided with a fuel atomizing orifice, a pressure valve disposedin the cylindrical portion of said cap member and adapted to receivefuel from said sleeve member, and a nozzle valve placed in thecylindrical portion of said cap member opposite said orifice andreceiving fuel from said pressure valve; said nozzle valve including aseat member having a seat and a bore adjacent to and having a greaterdiameter than said seat, said valve member having a frustoconicalportion adapted to seat on said seat, said valve member having acylindrical portion extending from the greater diameter end of saidfrustoconical portion and fitting into said bore.

References Cited in the file of this patent UNITED STATES PATENTS

